The present invention relates to a motor/gear-train drive unit, and particularly to a motor-vehicle power-window drive having a motor frame of a commutator motor, enclosed in a circumferential direction, with a gear case adjacent thereto at one of its axial ends and a closing bearing cap at its other end.
U.S. Pat. No. 3,463,951 discloses a drive unit that relates to such a motor-vehicle power-window drive.
In the drive unit of the patent, a magnet frame is inserted in a one-piece motor/gear-train case of flat design, from the initially open bearing-cap side. The magnet frame is spaced from the motor frame and supported by a spring element in a vibration-resistant manner. The case is fastened closed with screws. The bearing cap is seated on an axial abutment at the end face. A brush support plate with box-type brush holders for the commutator motor, intended as drive, is mounted in the bearing cap.
An attachment plug passes through the bearing cap in an insulated and sealing manner. On its inner surface, a free-standing soldering lug is provided for connecting leads running to the brush support plate. The rotor shaft is supported at one end in a cup-shaped bearing in the bearing cap. At its other end, which extends into the gear case and accommodates a worm gear, the rotor shaft is supported in a cylindrical roller bearing in the gear case, abutting by that end axially against a mushroom-shaped tip of a setscrew. That screw can be screwed externally to a greater or lesser axial depth into the gear case.
German Patent Publication C 10 31 878 discloses an arrangement for controlling and fixing the axial play of a rotor shaft, and more particularly that of a rotary transformer or the like. The transformer has a housing, open at one end, and is provided in the closed end wall with a first bearing for one end of the shaft, and at the open end with a cover plate with a second bearing for the other end of the shaft. The axial position of the cover plate, and hence the axial play of the shaft, is adjusted by rotating a retaining ring which is screwed into the housing and which secures the cover plate while a detent fixes the position of the retaining ring relative to the housing. With the cover plate, a brush support plate located axially in front of it and engaging it by means of projections corresponding to openings in the cover plate, can be axially positioned in a screw thread to be provided in the inner surface of the motor frame as the retaining ring is rotated.
Moreover, German Patent Publication C2-36 35 987 discloses an electrical machine in which an end shield, fabricated as a sheet-metal blank, is welded to the motor frame to permit dimensional tolerances of the shaft and of the motor frame to be compensated by varying the degree to which the end shield is pushed into the motor frame.